Abstract
The ability to compare incremental changes in Quality Adjusted Life Years (QALYs) generated by different condition-specific preference-based measures (CSPBMs), or indeed between generic measures, is often criticised even where the valuation methods and source of values are the same. A key concern is the impact of excluding key dimensions from a descriptive system. This study examines the impact of adding a generic pain/discomfort dimension to a CSPBM, the AQL-5D (an asthma-specific CSPBM), by valuing samples of states from the AQL-5D with and without the new dimension using an interviewer administered time trade-off with a sample of the UK general public. 180 respondents provided 720 valuations for states with and without pain/discomfort. As expected the additional pain/discomfort dimension was found to have a significant and relatively large coefficient. More importantly for comparing changes in QALYs across populations the addition of pain/discomfort significantly impacts on the coefficients of the other dimensions and the degree of impact differs by dimension and severity level. The net effect on the utility value depends on the severity of their state: the addition of pain/discomfort at level 1 (no pain/discomfort) or 2 (moderate pain/discomfort) significantly increased the mean health state values in an asthma patient population; whereas level 3 pain/discomfort (extreme) reduced values. Comparability between measures requires that the impact of different dimensions on preferences is additive, whether or not they are included in the classification system. Our results cast doubt on this assumption, implying that the chosen measure must contain all important and relevant dimensions in its classification system.
Highlights
Recent years has seen the rise of generic preference-based measures in populating cost per Quality Adjusted Life Years (QALYs) analyses, with the EQ-5D gaining a special status as the preferred measure for economic evaluations submitted to the National Institute for Health and Clinical Excellence of England and Wales (NICE, 2008)
Using one instrument in all studies ensures that different patient groups are being judged in terms of the same dimensions of health, using the same valuation methods and utility values obtained from the same sample
This study shows quite clearly that the content of the health state classification plays an enormous role in determining the values that are generated
Summary
One or more of the generic preference-based measures have been shown to perform poorly in some conditions, such as visual impairment in macular degeneration (Espallargues et al, 2005), hearing loss (Barton, Bankart, & Davis, 2004), leg ulcers (Walters, Morrell, & Dixon, 1999), and urinary incontinence (Haywood, Garratt, Lall, Smith, & Lamb, 2008) For this and other reasons many clinicians and researchers use condition-specific measures that are not preference-based. Using one instrument in all studies ensures that different patient groups are being judged in terms of the same dimensions of health, using the same valuation methods and utility values obtained from the same sample
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
